Rolling mill with means for roll deflection



ROLLING mm. mm mamas FOR ROLL DEFLECTION Filed July 12. 1966 J. A. TRACY Sept. 22, 1970 2 Sheets-Sheet l Fig.1

JOHN ANDRE TRACY p 22,1910 J. A. TRACY 3,529,462

ROLLING MILL WITH MEANS FOR ROLL DEFLECTION Filed July 1-2, 1966 2 Sheets-Sheet 2 Inventor United States Patent 3,529,462 ROLLING MILL WITH MEANS FOR ROLL DEFLECTION John A. Tracy, Bournemouth, England, assignor to The Loewy Engineering Company Limited, Bournemouth,

England, a corporation of Great Britain Filed July 12, 1966, Ser. No. 564,607 Int. Cl. B21b 27/00 US. Cl. 72-237 4 Claims ABSTRACT OF THE DISCLOSURE This application relates to a rolling mill having means for roll deflection comprising common power means used simultaneously on both bearing chocks of a roll of said mill at points spaced apart from the axis of said roll and adapted to impart forces to said chocks which are parallel to the roll axis and act in the vertical axial plane of that roll, so that the bearing chocks of said roll tilt in said plane and deflect said roll.

This invention relates to rolling mills and is concerned with means provided in a rolling mill for compensating those deflections of the mill rolls which occur during rolling as a result of the roll-separating force. Because of these deflections, the gap between the rolls of the mill in which rolled material is reduced in thickness will be wider in the middle region of the rolls than at their ends. Material which is reduced in a gap of this shape is consequently not of uniform thickness across its width, and is therefore unacceptable in many instances.

It has been attempted to remedy this deficiency by forming the rolls of a rolling mill with a camber so that, when the rolls were not under load, the gap between the rolls was narrower at the middle region of the rolls than at their ends. When the rolls were under load, the ensuing deflection caused the roll gap to widen in the middle, thereby reducing the difference in width between middle region and ends. However, equalisation of the roll gap could be achieved only in respect of that specific deflection of the rolls which was equal to the selected camber of the rolls. This meant that equalisation of the roll gap could only be effected for one specific roll-separating force, and hence for one specific set of rolling conditions.

It has been proposed to apply to the rolls of a rolling mill, during rolling, forces additional to the roll-separating force, which forces produce bending moments counteracting those produced by the roll-separating force. These forces were adjustable in accordance with the variations of the roll-separating force, so that the above-mentioned limitations were overcome. In this way, crown-control of a rolling mill could be obtained under all conditions under which a rolling mill could be expected to operate.

The means for producing the forces effecting crowncontrol consisted of hydraulic pressure units which acted on the ends of the rolls and whose pressure could be adjusted. In known rolling mills, the units were arranged either between two rolls at opposite sides of the roll-gap, these rolls being either the working rolls or the backing rolls of a mill, or between a roll and the housings of the rolling mill. In known rolling mills, the pressure units acted on separate secondary bearings mounted on the roll ends at points adjacent the bearing chocks of the roll, the secondary bearings being held against rotation so that the pressure units could have a stationary mounting in the mill. The known arrangements of pressure units, as well as their attachments and mountings in the mill, were of heavy and bulky design and, moreover, made it difficult to remove the rolls from the housings and to insert them therein.

It is an object of the present invention to provide in a rolling mill improved means for imparting a controllable deflection to one or more rolls of the mill for the purpose of obtaining in the mill a roll-gap of desired contour.

It is, in particular, an object of the present invention to provide in a rolling mill roll-deflecting means which are of simple design, take up little space, and can be readily fitted to or removed therefrom.

Another object of the invention is to provide in a rolling mill roll-deflecting means which are so arranged as not to obstruct removal or insertion of the roll.

According to the invention there are provided in a rolling mill, power means acting simultaneously on both bearing chocks of a roll at points spaced-apart from the axis of said roll and adapted to impart forces to said chocks which forces are parallel to the roll axis and act in the vertical axial plane of that roll. These forces cause the bearing chocks of a roll to tilt in that plane so as to deflect the roll supported in said chocks.

The direction of tilt of the chocks depends on the direction of the force acting on them and on the position of the point of application relative to the roll axis. It will be clear, therefore, that by reversing the direction of the force or by transferring its point of application to the other side of the roll axis, the direction in which a bearing chock tilts can be correspondingly reversed.

Preferably, two oppositely-directed forces are applied .to a bearing chock, thus producing a couple which tends to turn or tilt the chocks in the vertical axial plane of the roll supported by the chocks.

Several embodiments of the invention will now be described by way of example with reference to the accompanying drawings:

FIG. 1 is an elevation partly in section of a rolling mill equipped with roll-deflecting means according to the invention.

FIG. 2 is a section along the line IIII of part of the mill of FIG. 1.

FIG. 3 shows another embodiment of roll-deflecting means according to the invention.

FIG. 4 is a section along the line lV-IV of FIG. 3.

FIG. 5 shows a variant of the roll-deflecting means according to FIG. 3.

The rolling mill of FIG. 1 has two housings 10 joined together at their tops by a crossbeam 12. The mill, being of the four-high type, has two working rolls 14 defining between them a pass-opening for the rolled articles, and two backing rolls 16, one for each working roll. Bearing chocks 18 for the backing rolls are accommodated in windows 20 of the housings; bearing chocks 22 for the working rolls are seated in recesses of the chocks 18. The chocks 18 have axial extensions for accommodating bearing bushes 19 and are closed at their ends by caps which, for the sake of simplicity, are not separately shown in the drawings. The working rolls 14 are driven through spindles 24 from a source of power, not shown. The chocks 18 of the upper backing roll and the latter roll can be vertically displaced in the windows 20 by screwdown spindles 26 whereby the clearance between the working rolls and the pass-opening can be adjusted in width.

The above-described features of a rolling mill are all well-known.

During the operation of the mill, a force is set up which tends to separate the working rolls 14 from each other. This force has the effect of bowing the rolls 14 outwards, i,e., away from the pass-opening. Thus, the passopening becomes wider in its middle than at its ends.

According to the invention, there are fitted to the mill roll-deflecting means which act directly on the bearing chocks of the rolls. In the embodiments shown in the drawings, these roll-deflecting means act on the chocks 18 of the backing rolls 16, but it is understood that they can also act directly on the chocks 22 of the working rolls of either a four-high mill or of a two-high mill.

In the embodiment of FIGS. 1 and 2, the roll-deflecting means for each roll 16 comprise a set of four toggles 31, 32, 33, 34. Each of these toggles is hinged at its ends by pins 36 to lugs provided on the chocks 18, the toggles being so grouped around the axis of the rolls 16 that the toggles of a set are, as shown in FIG. 2, disposed symmetrically both with respect to the horizontal plane AA and the vertical plane BB of a roll 16. HOW- ever, this symmetrical arrangement is not necessary, though it is preferred. The toggles extend longitudinally of the roll 16 so that the pins 36 of a toggle are supported on the two chocks 18 at points situated on a line parallel to the axis of a roll 16. The knee-joints 38 of two toggles which are in the same vertical plane and belong to the same set are connected to each other by a link which consists of a hydraulic cylinder-andpiston unit 40 and the piston rod 42 of that unit. The axis of a unit 40 is perpendicular to the axis of a roll 16.

In FIG. 1, the toggles are shown in positions which they take up when the units .40 are not pressurised. The toggles are then almost, but not fully, stretched, with the toggles of the upper roll 16 forming a V pointing upwards, and those of the lower roll a V pointing downwards. Corresponding links of the toggles of a set are then parallel to each other.

On the admission of pressure fluid to the units 40, the knee-joints 38 of the toggles 31, 32 of a set are moved away from the knee-joints of the toggles 33, 34 of the same set, so that the lower toggles 33, 34 of the upper roll 16 and the upper toggles 33, 34 of the lower roll 16 become fully stretched while the remaining toggles 31, 32 are collapsed. Thus, the pins 36 of a set of toggles located on the chocks 18 at points near the pass-opening are pushed away from each other, while the pins 36 located on the chocks at points remote from the pass-opening are drawn together. The forces acting on the pins apply couples to the chocks which tilt or turn them in the vertical axial plane of roll 16 and deflect the roll 16 supported on those chocks in the same plane.

As will be seen from FIG. 1, this results in a downward deflection of the upper roll 16 and an upward de flection of the lower roll 16. These deflections are also imparted to the working rolls, so that the middle of the passopening becomes narrower than before.

The pressure exerted by the hydraulic units 40 on the kneejoints 38 and the forces transmitted to the chocks 18 through the toggles and their pins 36 is controllable by any well-known and suitable means, so that the amount of deflection of the rolls 16 can be adjusted.

It will be seen from FIG. 1 that the hydraulic units 40 are exclusively supported on the toggles and not on the mill housings, so that the latter are not subjected to any extra load by the hydraulic units.

In normal practice, a small deflection of the rolls 16 and 14, and consequently only a slight rotation of the chocks will be required. The bearings which support the roll necks in the chocks are longer than usual in order to guide the roll necks during roll deflection.

The parts supporting the roll necks and/ or the chocks may have curved surfaces of contact to enable the chocks and necks to turn or tilt without jamming.

While in the foregoing the operation of the roll-deflect ing means according to the invention has been described for the purpose of narrowing the pass-opening at its centre, it is also possible to use the roll-deflecting means for the reverse operation, viz., for widening the pass opening at its centre. In the latter case, the direction of the forces acting on the chocks must be reversed. This can be achieved by reversing the no-load positions of the toggles so that the toggles of the upper roll form a d downwardly-pointing V, and those of the lower roll an upwardly-pointing V.

The use of toggles in the roll-deflecting means according to the invention has the advantage of requiring only a relatively small force in the hydraulic units for a given turning or tilting moment applied to the chocks, so that these units can be made comparatively small and light in weight. Furthermore, the toggles, together with the hydraulic units, can be easily fitted to or removed from a rolling mill and do not necessitate any large-scale alterations of the mill components.

FIGS. 3 and 4 show an alternative form of roll-deflecting means according to the invention. These means include hydraulic piston-and-cylinder units 50 whose axes are parallel to those of the rolls 16. The cylinders 52 of the units are attached to one of the chocks 18 of a roll 16 and their pistons are attached to the other chock of the same roll through rods 54 extending longitudinally of the roll. Alternatively, the rods 54 may be attached to the cylinders, while the pistons are attached to the chocks, or the units 50 may be arranged at a distance from both chocks with their cylinders and pistons attached to the chocks by separate rods. Finally, the units may each have two oppositely arranged rams co-operating with a common or with separate pressure chambers in the same cylinder. Preferably, the units are of the double-acting type so that they can be selectively used for subjecting the chocks either to thrusts, whereby they are moved away from each other, or to pulls, whereby they are drawn together.

The pressure of the fluid in the hydraulic units 50 is controllable by any suitable and well-known means, and thereby also the forces to which the units subject the chocks.

In FIGS. 3 and 4, each roll 16 has four hydraulic units 50 and the same number of rods 54, the grouping of the units around the axis of a roll 16 being similar to that of the toggles 31 to 34 shown in FIG. 1. The units which act on parts of the chocks near the working rolls subject the chocks to thrusts so as to move the chocks of a roll away from each other, while those units which act on parts of the chocks remote from the working rolls subject the chocks to pulls, drawing the chocks of a roll together. The result is that the chocks are subjected to couples of forces in the vertical axial plane of a roll which turn or tilt then and deflect the rolls in such a direction that the centre of the pass-opening becomes narrower than before. The reverse effect on the pass-openingthe Widening of its centreis obtained by reversing the direction of the forces acting on the chocks. This reversal can easily be effected by the use of double-acting hydraulic units 50.

It will be understood that the roll-deflecting means according to FIGS. 3 and 4 can also be applied to chocks 22 of the working rolls 14.

The embodiment of FIG. 5 is similar in all respects but one to that of FIG. 4, the difference being the substitution of a single hydraulic unit 50 and rod 54 for the two units and rods provided in FIG. 4 acting on those parts of the chocks which are remote from the working rolls 14. The single unit with its rod is arranged in the vertical axial plane of a roll and is preferably made twice as powerful as the hydraulic units acting on the part of the chocks near the working roll.

Inasmuch as the roll-deflecting means according to the invention can be selectively used both for narrowing or for widening the centre of a passopening, these means can be employed equally in rolling mills whose rolls have no camber or a small camber, and in mills whose rolls have a large camber. In the former case, the camber does not exceed in magnitude the maximum deflection of a roll under normal operating conditions, while in the latter case the camber is greater than the maximum deflection.

By controlling the pressure in the hydraulic units 40 or 50, it is possible to obtain a deflection of the Working rolls which fully compensates deformation of the passopening caused by the roll-separating force. The pass opening will then be of uniform width from end to end.

In the foregoing examples, two oppositely-directed forces are applied to each chock at points situated diametrically opposite each other with respect to the axis of the deflected roll, whereby couples of forces are produced tilting the chocks in the vertical axial plane of the roll.

The invention can also be carried out in such a way that only a single force is applied to a chock at a point spaced-apart from the roll axis. In this case, a bending moment instead of a couple is applied to the chock. Thrust bearings are then provided in the chocks.

In all embodiments described here, the roll-deflecting forces are directly applied to those chocks which support the rolls in the mill housings, so that separate chocks or bearings for the roll-deflecting means are not required.

The invention has been described in the foregoing in relation to a metal-rolling mill, but it is equally applicable to rolling mills for plastic articles, such as sheets.

I claim:

1. A rolling mill having rolls, bearing chocks for said rolls and means acting simultaneously on the bearing chocks of at least one of said rolls to deflect at least one of said rolls, said means comprising at least one poweroperated toggle, the ends of said toggle being pivoted to said bearing chocks at points which are offset from the horizontal axial plane of said roll, so that said toggle imparts to said bearing chocks bending moments in the vertical axial plane of said roll, the bending moments acting on both bearing chocks having opposite directions.

2. A rolling mill according to claim 1 in which power means in the form of a hydraulic cylinder and piston unit are attached to the knee joint of said toggle.

3. A rolling mill according to claim 1 in which two superposed toggles are arranged in respect of at least one roll, the ends of one of said toggles being pivoted to said bearing chocks at points situated above the horizontal plane of said roll and the ends of the other toggle being pivoted to said bearing chocks at points situated below the horizontal plane of said roll.

4. A rolling mill according to claim 3 in which power means in the form of a hydraulic cylinder and piston unit are attached to the knee joints of two superposed toggles.

References Cited UNITED STATES PATENTS 381,746 4/1888 Wright 72244 2,611,150 9/1952 Goulding 72245 2,897,538 8/1959 Shapiro et al. 72245 3,171,305 3/1965 Stone 72--245 3,250,105 5/ 1966 Stone 72243 3,442,109 5/1969 Diolot 72240 FOREIGN PATENTS 747,347 4/1956 Great Britain.

LOWELL A. LARSON, Primary Examiner 

